This invention relates to magnetic tape cartridges, and more particularly to a magnetic tape cartridge that permits easy mounting of a slide door openably attached to an opening through which a magnetic tape may be drawn out.
LTO (Linear Tape Open) standard-compliant magnetic tape cartridges have prevailed in the realm of the magnetic tape cartridges used as an external recordable medium for data backup of a computer or the like. The magnetic tape cartridge of this type includes a single reel of magnetic tape and other components in a cartridge case comprised of a lower half and an upper half. At a side of the cartridge case, an opening through which the magnetic tape is drawn out is formed across the lower and upper halves. A slide door shaped like a thin plate for opening/closing the opening is slidably fitted in shallow guide grooves respectively formed in the lower and upper halves and kept in such a position as to close the opening under the stress of a spring member.
When the magnetic tape cartridge of this type is loaded in a drive that reads and writes data on the magnetic tape, a loading mechanism in the drive opens the slide door of the opening, and a single reel of magnetic tape is drawn out through the opening. The magnetic tape that is drawn out, then, runs across a head of the drive; thereby data is recorded on or read out of the magnetic tape. When the magnetic tape cartridge is unloaded from the drive, the slide door is moved by the action of the spring member to the position in which the slide door may close the opening in order to keep out dust.
In an assembly process of the above-described magnetic tape cartridge, a lower edge of the slide door is fitted in the shallow guide groove of the lower half of the cartridge case under the stress of the spring member toward a direction in which the slide door is closed. Thereafter, the upper half is combined with the lower half, and thus an upper edge of the slide door is fitted in the shallow guide groove of the upper half, so that the slide door as well as the spring member is mounted in the cartridge case.
A description will be given more specifically of exemplified mounting operations of the slide door in the conventional magnetic tape cartridge as described above with reference to FIGS. 23A-C and 24. Referring now to FIG. 23A, there is shown, as one example of the above slide door, a slide door A3 shaped like a laterally-oblong thin plate having upper and lower edges slidably fitted respectively into shallow guide grooves A2 of an upper half (not shown) and lower half A1 of the cartridge case. At a rear end (or side facing a direction in which the slide door A3 moves to open the opening) of the slide door A3 is formed a spring anchor portion A6 that anchors a distal end of a pressurizing spring arm A5 of a torsion coil spring A4 as the spring member. As shown in FIG. 23A, which is a magnified view of this example, the lower half A1 includes a sidewall A8 in which an opening A7 is made. The torsion coil spring A4 as the spring member, and the slide door A3 are fitted into the guide groove A2 formed along an inside of the opening A7 provided in the sidewall A8 of the lower half A1. In that event, the slide door A3 is mounted in the cartridge case in such a manner that the slide door A3 may be kept under the stress of the torsion coil spring A4 toward a direction in which the slide door A3 moves to close the opening, and that a front edge A9 thereof is in contact with a contact portion A11 provided in a sidewall A10 of the lower half A1 of the cartridge case, as shown in FIG. 23B, which is a cross-sectional view taken along line X—X in FIG. 23A.
Turning to FIG. 24, in contrast, there is shown, as another example of the above slide door, a slide door B4 shaped like a laterally-oblong thin plate having upper and lower edges slidably fitted respectively into shallow guide grooves B2 of an upper half (not shown) and a lower half B1 of the cartridge case. At a rear end (or side facing a direction in which the slide door B4 moves to open the opening) of the slide door B4 is provided a spring support rod B3 so as to project from a vertically middle position of the rear end toward rearward. At a distal end of the spring support rod B3 is formed a stopper head B5 having a slot that may reduce a diameter of the head. A thin-helix long compression coil spring B6 fitted in the spring support rod B3 of the slide door B4 with the diameter of the stopper head B5 at the distal end of the spring support rod B3 reduced is used for a spring member. The diameter of the fitted stopper head B5 expands by the action of elastic recovery, with the result that the compression coil spring B6 is secured so as not to come off; the compression coil spring B6 is wound around the spring support rod B3 in a manner that permits compressive deformation.
When the slide door B4 is fitted in the lower half B1 of the cartridge case as shown in FIG. 24, the slide door B4 is slightly tilted so that the spring support rod B3 declinates a little, and the distal end of the spring support rod B3 including the stopper head B5 is brought into contact with a support rod receiving groove B8 on a support rod receiving block B7 provided on the lower half B1 of the cartridge case, and is properly positioned. Next, the slide door B4 is slightly moved in a direction to open the opening (to the left in FIG. 24) so that the stopper head B5 may pass on a side of a spring receiving piece B9 along the support rod receiving groove B8. Thereafter, the slide door B4 is lowered toward the guide groove B2 in the lower half B1 while a horizontal orientation of the slide door B4 is being restored, and the lower edge thereof is fitted into the guide groove B2.
The example as shown in FIGS. 23A through 23C keeps the slide door A3 open upside until an upper half (not shown) is combined with the lower half A1. Moreover, the guide groove A2 that receives the slide door A3 is shallow. Accordingly, the slide door A3 tends to fall in a direction perpendicular to a face of the slide door A3, particularly, in a direction indicated by an arrow YA inward of the cartridge case as shown in FIG. 23C that is a section taken along line Y—Y in FIG. 23A. Falling of the slide door would make the slide door A3 difficult to neatly fit into the guide groove A2 in the lower half A1 or the guide groove in the upper half (not shown), in some instances.
On the other hand, the example as shown in FIG. 24 would have the spring support rod B3 deviated from a direction extending from the support rod receiving groove B8, or would have the spring support rod B3 curved, when the distal end of the spring support rod B3 projected from the slide door B4 is brought into contact with the support rod receiving groove B8 on the support rod receiving block B7 provided on the lower half B1, and is positioned. Consequently, The stopper head B5 on the distal end of the spring support rod B3 could not be properly positioned in the support rod receiving groove B8, so that the compression coil spring B6 wound around the spring support rod B3 would possibly fail to be hooked on the spring receiving piece B9.
In short, during an assembly process of the conventional magnetic tape cartridge, the slide door having a lower edge to be fitted in a shallow guide groove in a lower half of a cartridge case would likely fall when the lower edge is fitted into the shallow guide groove in the lower half, and a stress of the spring member would possibly lift up the end of the slide door at a side facing a direction in which the slide door moves to open the opening, so as to get off the guide groove. Moreover, the compression coil spring wound around the spring support rod of the slide door would fail to be securely hooked on the spring receiving piece. Therefore, when the slide door is mounted in the cartridge case while the lower half and upper half of the cartridge case are combined during the assembly process of the conventional magnetic tape cartridge, the lower edge of the slide door would not be neatly fitted into the guide groove in the lower half, or the upper edge of the slide door would not be neatly fitted into the guide groove in the upper half; thereby failure in mounting the slide door would likely occur. This tendency would not be negligible when the slide door is mounted using an assembly robot.